docs : Todo앱 예제, DAO에서 Read 반환타입이 Flow, ViewModel 프로퍼티도 State<List<Todo>>

[philipy355]

Todo앱

• 강의에 MainViewModel init부분
• Room Version에 따른 Dao CRUD suspend 사용시 에러
• main-comonents에 TodoItem.kt에서 callBack onClick 사용이 누락되어 있는거 같음
• 그외 참고사이트 자동생성? https://velog.io/@max9106/IntelliJ-Live-Template
• 강사님 git url : https://github.com/junsuk5/android-compose/blob/master/examples/TodoList/app/src/main/java/com/example/todolist/ui/main/HomeScreen.kt

• dependency

  // Room
      def room_version = "2.5.2"
      implementation "androidx.room:room-runtime:$room_version"
      kapt "androidx.room:room-compiler:$room_version"
  
      //https://velog.io/@dear_jjwim/%EC%95%88%EB%93%9C%EB%A1%9C%EC%9D%B4%EB%93%9C-Room-%EA%B4%80%EB%A0%A8-%EC%98%A4%EB%A5%98-%ED%95%B4%EA%B2%B0-Execution-failed-for-task-appkaptDebugKotlin
      kapt "org.xerial:sqlite-jdbc:3.36.0"
  
      // optional - Kotlin Extensions and Coroutines support for Room
      //noinspection GradleDependency
      implementation "androidx.room:room-ktx:$room_version"

• Composable TodoItem

  @SuppressLint("InvalidColorHexValue")
  @Composable
  fun TodoItem(
      todo: Todo,
      onClick: (todo: Int) -> Unit = {},
      onDeleteClick: (id: Int) -> Unit = {},
  ) {
      val format = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault())
  
      Column(
          Modifier
              .padding(8.dp)
              .clickable { onClick(todo.uid) }
      ) {
          Row(
              verticalAlignment = Alignment.CenterVertically,
          ) {
              // 삭제 아이콘
              Icon(
                  modifier = Modifier
                      .padding(end = 8.dp)
                      .clickable { onDeleteClick(todo.uid) },
                  painter = painterResource(id = R.drawable.ic_delete_black_24dp),
                  contentDescription = null,
                  tint = Color(0xFFA51212),
              )
  
              // 내용
              Column(
                  modifier = Modifier.weight(1f),
              ) {
  
                  Text(
                      format.format(Date(todo.date)),
                      color = if (todo.isDone) Color.Gray else Color.Black,
                      style = TextStyle(textDecoration = if (todo.isDone) TextDecoration.LineThrough else TextDecoration.None),
                  )
                  Text(
                      todo.title,
                      color = if (todo.isDone) Color.Gray else Color.Black,
                      style = TextStyle(textDecoration = if (todo.isDone) TextDecoration.LineThrough else TextDecoration.None),
                  )
              }
  
              if (todo.isDone) {
                  // 완료 아이콘
                  Icon(
                      painter = painterResource(id = R.drawable.ic_done_black_24dp),
                      contentDescription = null,
                      tint = Color(0xFF00BCD4),
                  )
              }
          }
      }
  }
  
  @Preview(showBackground = true)
  @Composable
  fun TodoItemTruePreview() {
      TodoItem(todo = Todo("숙제", Date().time, true))
  }

• MainActivity

  class MainActivity : ComponentActivity() {
  
      override fun onCreate(savedInstanceState: Bundle?) {
          super.onCreate(savedInstanceState)
          setContent {
              val viewModel : MainViewModel = viewModel(
                  factory = TodoAndroidViewModelFactory(application)
              )
  
              MainScreen(viewModel = viewModel)
          }
      }
  }

• MainViewModel

  //viewmodel에는 Data 조작을 위해 TodoRepository를 받도록 한다.
  class MainViewModel(
      application: Application,
      private val todoRepository: TodoRepository
  ) : AndroidViewModel(application) {
  
      private val _items = mutableStateOf(emptyList<Todo>())
      val items : State<List<Todo>> = _items
  
      //이 부분 강의에서 생략된듯?
      init {
          viewModelScope.launch {
              todoRepository.obserbTodos()
                  .collect { todos ->
                      _items.value = todos
                  }
          }
      }
  
      private var recentlyDeleteTodo : Todo? = null
  
      fun addTodo(text : String){
          viewModelScope.launch {
              todoRepository.addTodo(Todo(title = text))
          }
      }
  
      fun toggle(uid : Int) {
          val todo = _items.value.find { todo -> todo.uid == uid }
          todo?.let {
              viewModelScope.launch {
                  todoRepository.updateTodo(it.copy(isDone = !it.isDone).apply {
                      //uid는 copy가 안되서
                      this.uid = it.uid
                  })
              }
          }
      }
  
      fun delete(uid : Int) {
          val todo = _items.value.find{ todo -> todo.uid == uid }
          todo?.let {
              viewModelScope.launch {
                  todoRepository.deleteTodo(it)
                  recentlyDeleteTodo = it
              }
          }
      }
  
      fun restoreTodo(){
          viewModelScope.launch {
              //recentlyDeleteTodo가 null이면 ?:에 의하여 launch를 취소한다.
              todoRepository.addTodo(recentlyDeleteTodo ?: return@launch)
              recentlyDeleteTodo = null
          }
      }
  }
  
  class TodoAndroidViewModelFactory(
      private val application: Application,
      private val repository: TodoRepository = TodoRepositoryImpl(application = application),
  ) :
      ViewModelProvider.AndroidViewModelFactory(application) {
      override fun <T : ViewModel> create(modelClass: Class<T>): T {
          if (modelClass.isAssignableFrom(MainViewModel::class.java)){
              return MainViewModel(application, repository) as T
          }
          return super.create(modelClass)
      }
  }

• Repository

  interface TodoRepository {
      fun obserbTodos() : Flow<List<Todo>>
  
      suspend fun addTodo(todo : Todo)
  
      suspend fun updateTodo(todo : Todo)
  
      suspend fun deleteTodo(todo : Todo)
  }
  
  class TodoRepositoryImpl(application: Application) : TodoRepository {
      private val db = Room.databaseBuilder(
          application,
          TodoDatabase::class.java,
          "todo-db",
      ).build()
  
      override fun obserbTodos(): Flow<List<Todo>> {
          return db.todoDao().todos()
      }
  
      override suspend fun addTodo(todo: Todo) {
          return db.todoDao().insert(todo)
      }
  
      override suspend fun updateTodo(todo: Todo) {
          return db.todoDao().update(todo)
      }
  
      override suspend fun deleteTodo(todo: Todo) {
          return db.todoDao().delete(todo)
      }
  }

• Room DB (DataSource & Model)

  @Entity(tableName = "todo")
  data class Todo(
      val title : String,
      val date : Long = Calendar.getInstance().timeInMillis,
      val isDone : Boolean = false,
  ) {
      @PrimaryKey(autoGenerate = true)
      var uid : Int = 0
  }
  
  @Database(entities = arrayOf(Todo::class), version = 1)
  abstract class TodoDatabase : RoomDatabase(){
      abstract fun todoDao() : TodoDao
  }
  
  @Dao
  interface TodoDao {
      //flow는 비동기적인 데이터처리에 적합하다.
      @Query("SELECT * FROM todo ORDER BY date DESC")
      fun todos() : Flow<List<Todo>>
  
      @Insert(onConflict = OnConflictStrategy.REPLACE)
      suspend fun insert(todo : Todo)
  
      @Update
      suspend fun update(todo : Todo)
  
      @Delete
      suspend fun delete(todo : Todo)
  }